Well perforating assembly



July 1 1955 E. GILLI NGHAM ETAL 3,194,159

WELL PERFORATING ASSEMBLY Filed Nov. 20, 1962 INVENTORS Ernesr L.Gllhnghum Jack O. Grunwold BY Wm.

ATTORNEY United States Patent 0 3,194,159 WELL PERFORATIN G ASSEMBLYErnest L. Gillingham, Fort Worth, and Jack 0. Grunwald,

This invention relates to well perforating assemblies and particularlyto an improved bull nose for use in Well perforating assembliesutilizing shaped explosive charge units having frangible cases.

The widespread use of permanent well completion techniques, in thepractice of which tubing is run into a well and permanent well headequipment is installed prior to perforating the well, has spurreddevelopment ;in the application for United States Letters Patent filedOctober 8, 1954 byBlake M. Caldwell and Harrold D. Owen, Serial Number461,236, now Patent No. 3,067,679, entitled Well Perforating Assembly.

The perforating apparatus disclosed in the foregoing patent applicationprovides a firing head from which is suspended an elongated carrierhaving pivotally mounted, shaped explosive charge, perforating unitsthereon. The shaped charge units are urged by resilient means to assumea position transverse to the carrier but are held within the carrier inan. axially aligned position with respect to the carrier by interlockmeans provided on each charge unit. An explosive release means, such asa squib, abuts a detent on a terminal shaped charge unit to retain thecharges in. axial alignment. After the perforating apparatus is run outof the lower end of the tubing, the squib is detonated from the earthssurface and the terminal shaped charge unit pivots to the transverseposition and releases the charge units thereabove to pivot to transversepositions. When the charge units are all in positions transverse to thecarrier axis, the units are fired to perforate the. well by closing aswitch on the earths surface. The squib of the foregoing perforatingapparatus has, on occasion, been responsible for damage to the terminalcharge unit. In such apparatus, the squib was positioned immediatelyadjacent one end of the terminal shaped charge unit and in abutment withthe detent on that end of the charge unit. When the squib was fired, theforce of the explosion would, on occasion, crack or otherwise damage theend of the frangible metal case of the charge unit, causing the unit toleak and fail to function properly.

' Recently, glass-cased shaped charge units for this particularperforating apparatus have come into use; such units are even moresusceptible to damage from the blast effects of the squib than aremetal-casedunits.

The present invention relates to improvements in the ice perforatingapparatus of the aforesaid Caldwell and Owen application, specificallyto. improvements in the means for releasing the terminal charge unit forpivoting. The present invention also relates to improvements in thevarious forms of release mechanisms for releasing the terminalpivotable. shaped charge in a well perforating assembly disclosed inanother application for United States Letters Patent of Blake M.Caldwell and Harrold D. Owen filed February 7, 1961, Serial No. 87,714,for Well "Perforating Assembly, which application is a continuation ofapplication Serial No. 570,004 filed March 7, 1956, now abandoned.

It is, therefore, an object of this invention to provide a perforatingassembly having a shaped charge unit release means which, in operation,will not damage the shaped charge units.

Another object of this invention is to provide an improved bull nosestructure for the lower end of a perforating assembly, which structureincludes; a charge unit release means. The bull nose structure is simpleto construct and economical to manufacture.

The foregoing and other objects and advantages of the invention as mayappear hereinafter are realized in a well perforating assembly having acarrier and a shaped explosive charge unit with a frangible case. Meansare provided pivotally mounting the unit on the carrier in a firstposition. The unit is pivotabl-e in the mounting means to a secondposition. Means are provided biasing the unit to pivot from the firstposition to the second position. Detent means are provided on the unitadjacent the frangible case. A frangible cantilever stop member hasitssupported end fixed to the carrier at a point remote from the frangiblecase and its unsupported end projecting into engagement with the detentmeans to restrain the unit from pivoting to the second position.Explosive means are provided which are adapted to sever the unsupportedend of the stop member from the supported end oflthe stop member topermit the unit to pivot to the second position. i

In its more specific aspects, the present invention is realized in abull nose for well perforating assemblies which have pivotally mountedshaped explosive charge units axially aligned with the longitudinal axisof the assembly. The bull nose has a hollow, open-ended main body with agenerally cylindrical side wall. An integrally formed, longitudinallyextending web projects from the interior of the side Wall. A frangible,upstanding stop post is integrally formed with the Web and has an upperportion extending thereabove. The stop post provides a downwardlyopening axial bore in the lower portion thereof adapted to receive anexplosive squib. The bore in the stop post terminates a substantialdistance from the upper end of the stop post.

In the drawings: r

FIG. 1 is a side elevational view, partly in vertical, axial section, ofthe lower end of a perforating assembly having an axially aligned,.pivotable shaped charge unit restrained by the bull nose of the presentinvention;

FIG. 2 is a side elevat-ional view, with portions broken away, of theperforating assembly of FIG. l showing the charge restraining portion ofthe bull nose destroyed and the shaped charge unit pivoted to thehorizontal position; r r

' 12 after the units pivot to the horizontal position.

FIG. 3 is a perspective view of the bull nose of the assembly of FIGS. 1and 2 with a portion broken away; and

FIG. 4 is a plan view of the bull nose.

For a detailed description of the general perforating assembly,reference is made to the aforementioned Caldwell and Owen application,Serial No. 461,236. The present disclosure is concerned with thecooperation of the lower end of an elongated carrier, the pivotallymounted lowermost shaped charge unit, and the improved bull nosestructure carrying the destructible restraining means for maintainingthe shaped charge units in axial alignment with respect to the carrier.

Referring now toFIGS. 1 and 2, there is shown a generally tubular,elongated carrier it) having longitudinally offset apertures 11 onopposite sides thereof. Shaped charge units 12 are pivotally mountedwithin the carrier as by pins 13. Each one of the shaped charge units isbiased to extend horizontally by means of spring 14. The charge unitsare locked in axial disposition with respect to the carrier byinterlocking detents (not shown) carried by each of the charge units.The detent 15 on the lower end of the bottom charge unit is engaged byan elongated, vertically mounted, frangible, cantilever stop post 16which is a part of a bull nose structure, designated generally 17, thatis attached to the lower end of the carrier by screws 18. Thus, it isseen that the stop post 16 is the element that maintains the shapedcharges in axial disposition with respect to the carrier against theurging of the springs 14. The stop post 16 provides a downwardly openingaxial bore 19 in the lower portion thereof.v An explosive element orsquib, designated generally 20, is received in the bore 19 and isretained therein by the wedging action of a helically wound portion ofone of the lead wires 21 which also serves to ground one leg of thesquib to the carrier. A second lead wire 22 connects the squib through aswitch (not shown) to a source of electrical energy at the surface ofthe earth. The squib includes a metal case 38 having a rubber plug 39crimped into the lower end. The plug is moulded around the lead wires21, 22 whose ends project above the top of the plug and are connected bya fusible bridge Wire 40. An ignition charge 4-1 is provided surroundingthe bridge wire. A shearing charge 42 of a compressed detonatingexplosive is contained in the case above the ignition charge. The topsurface of the shearing charge is provided with a conical recess whichreceives an inverted,'conically shaped, inert barrier plug 43 thatextends into contact with the integral sealed end of the case 38. Thebarrier plug may be made of any suitable material, such as compressedaluminum powder, which will effectively deflect the major portion of theenergy .of the detonating shearing charge 42 transversely to the axis ofthe squib. A squib having a construction similar to that set forth aboveis commercially available from the E. I. du Pont de Nemours & Co., Inc.as the 13-868 Combination Primer. A pressure-resistant, electricblasting cap 23 is positioned in the hollow interior of the bull nose'17. One lead wire 24 of the blasting cap extends upwardly through thecarrier to a switch (not shown) and, thence, to a source of electricalenergy at the surface of the earth. The other lead wire 25 is groundedby lug 37 to the bull nose 1'7, and through it to the carrier 10. Alength of detonating fuse 2%, such as 70 gr. RDX Hycar CoveredHV'Primacord, extends upwardly through the carrier and is positioned tobe in detonating contact with each of the shaped charge units The lowerend of the fuse is crimped into the end of a blasting cap 23. Theblasting cap is covered by a synthetic rubber waterproof sleeve 27 whichextends above the upper end of the cap and is sealed at each end byseizing 28, 28. A similar sleeve 29 covers a splice in lead wire 24.These sleeves not only serve to waterproof the blasting cap and wiresplice, but also act to protect these items from damage that might becaused by flying metal particles upon detonation of the squib 20.

Referring now to FEGS. l, 3 and 4-, the bull nose 17 has a main bodywith two generally semi-cylindrical, opposite side wall portions 30 andZitla. The semi-cylindrical side wall portion 39 has a radius equal thatof the carrier 19 and is adapted to be slidingly received within thelowermost aperture 11 at the end of the carrier it). The outercylindrical side wall portion 39a has a radius slightly smaller thanthat of the carrier and is adapted to make a sliding fit within thelower end of the carrier, as may be seen in FIG. 1. This constructionassures that the bull nose will always be inserted in the lower end ofthe carrier with the stop post in proper disposition to contact thedetent on the lowermost shaped charge. Oppositely disposed, fiat sideportions 36 of the bull nose main body provide clearance for dimpled-inportions of the carrier 10 surrounding the holes (not shown) whichaccept the fiat head screws 18. The bottom portion 31 of the bull noseis tapered inwardly to guide the perforating assembly through tubing andprevent the assembly from hanging up on any projections that may bepresent within the tubing when the assembly is run into the well. Alarge opening 32 is provided in the bottom of the bull nose to permitwell bore fluids to flew up through the perforating assembly therebyincreasing the speed at which the assembly may be run into the well. Theopening also enhances the breakup of the frangible bull nose into smallsized debris when the shaped charge units are detonated. Alongitudinally extending web 33 is integrally formed with and extendsradially inwardly from the interior of the side wall portion Etta. Thelower portion of stop post 16 is attached to the upper portion of theinwardly facing edge of web 33 by any suitable means, for example, bybeing integrally formed therewith, as shown. The bore 19 in the lowerportion of the stop post 16 terminates at a transverse wall 34 that islocated above the top edge of web 33. The upper portion of the stop postis provided with an axial bore 35 that terminates on the upper side ofthe transverse wall 34. The side wall of the lower portion of the stoppost is sufiiciently thin to be readily sheared transversely bydetonation of the squib 29. The upper bore 35 and lower bore 19 areillustrated as being substantially equal in length and, thus, thetransverse wallfid is located in the middle of the stop post. Forpurposes of this invention, it is not essential that the bore 19 in thelower portion of the stop post be of any specific depth, but only thatthis bore terminate a sufficient distance below the end of the lowermostshaped charge unit 12 so that detonation of the squib 20 will not damagethe lowermost shaped charge unit. If desired, the upper portion of thestop post may be made solid by omitting the bore 35 therein. The entirebull nose assembly 17 is preferably energy to the squib 20. The squibfires and shears the frangible stop post 16 immediately below thetransverse wall 34 as may be seen in FIG. 2. The presence of the inertbarrier plug 43 in the top of the squib directs the major portion of theexplosive energy transversely to the axis of the squib and stop post 16.This laterally directed energy is concentrated on the annular thin wallsection of the stop post 16 lying between the upper edge of the web 33and the bottom of the transverse wall 34. The spring 14 attached to thelowermost shaped charge unit 12,

causes the charge to pivot to the horizontal position and, in so doing,the detent 15 on the lower end of the charge unit kicks the uppersheared-off portion of stop '5 post 16 outside of the carrier. After allthe charge units have pivoted to the horizontal position, electricalenergy is supplied to the blasting cap 23 to fire the detonating fuse 26which, in turn, fires the shaped charge units 12.

By virtue of being enclosed in a downwardly opening bore which is spaceda substantial distance from the lower end of the bottom shaped chargeunit, the squib can be safely detonated Without any danger of damagingthe frangible case of the adjacent charge unit. Bull noses constructedin accordance with the present invention eliminate damage to pivotableshaped charge units 12 having outer cases made of highly frangibleglass.

While there has been described what is at present considered a preferredembodiment of the present invention, it will be apparent to thoseskilled in the perforating art that various modifications and changesmay be made without departing from the essence of the invention.Therefore, such modifications and changes are intended to be covered ascome within the true scope and spirit of the appended claims.

We claim:

1. A well perforating assembly comprising:

(a) a carrier;

(b) a shaped explosive charge unit having a frangible case;

(c) means pivotally mounting said unit on said carrier in a firstposition, said unit being pivotable in said mounting means to a secondposition;

(d) means biasing said unit to pivot from said first position to saidsecond position;

(e) detent means on said unit adjacent to said frangible case;

(f) a frangible cantilever stop member having its supported end fixed tosaid carrier at a point remote from said frangible case and itsunsupported end projecting into engagement with said detent means torestrain said unit from pivoting to said second position; and

(g) an explosive squib located adjacent the supported end of said stopmember and adapted upon detonation to sever the unsupported end of saidstop member from the supported end of said stop member to permit saidunit to pivot to said second position.

2. In a well perforating assembly the combination comprising:

(a) an elongated carrier;

(b) a terminal shaped explosive charge unit having a frangible case,said unit being pivotally mounted adjacent one end of said carrier inaxial disposition with respect to said carrier;

(c) detent means on the end of said shaped explosive charge unit facingsaid one end of said carrier;

(d) resilient means urging said shaped explosive charge unit to pivotfrom said axial disposition;

(e) frangible restraining means attached to said carrier and engagingsaid detent means to restrain said shaped explosive charge unit in saidaxial disposition;

(f) an explosive squib positioned within a downwardly opening boreprovided in a portion of said restraining means spaced a substantialdistance from the end of said shaped explosive charge, said squibadapted to fragmentize a portion of said restraining means upondetonation to permit said shaped explosive charge unit to pivot fromsaid axial disposition; and

(g) said bore in said restraining means having an end wall spaced belowsaid end of said shaped explosive charge unit to prevent damage to saidcharge unit when said squib is detonated.

3. In a well perforating assembly the combination comprising:

(a) an elongated carrier;

(b) a terminal shaped explosive charge unit having a frangible case,said unit being pivotally mounted adjacent one end of said carrier inaxial disposition with respect to said carrier;

(c) detent means on the end of said shaped explosive charge unit facingsaid one end of said carrier; (d) resilient means urging said shapedexplosive charge unit to pivot from said axial disposition; (e) afrangible, elongated restraining member axially disposed with respect tosaid carrier and having one end engaging said detent means to restrainsaid shaped explosive charge in said axial disposition;

(f) means mounting said restraining member on said carrier; i j

(g) said restraining member providing a downwardly opening, axial boreat the end opposite said one end, the upper end of said bore beingspaced a substantial distance from said end of said shaped explosivecharge;

(h) an explosive squib received in said bore; and

(i) said restraining member being adapted to shear transversely adjacentthe upper end of said squib upon detonation of said squib to permit saidshaped explosive charge to pivot from said axial disposition withoutdamage to said charge for detonation of said squib.

4. In a well perforating assembly the combination comprising:

(a) an elongated carrier;

(b) a terminal shaped explosive charge unit having a frangible case,said unit being pivotally mounted adjacent one end of said carrier inaxial disposition with respect to said carrier;

(0) detent means on the end of said shaped explosive charge unit facingsaid one end of said carrier; ((1) resilient means urging said shapedexplosive charge unit to pivot from said axial disposition;

(e) a frangible, elongated restraining member axially disposed withrespect to said carrier and having one end engaging said detent means torestrain said shaped explosive charge in said axial disposition;

(f) means mounting said restraining member on said carrier;

(g) said restraining member providing a downwardly opening, axial bore.at the end opposite said one end, the upper end of said bore beingspaced a substantial distance from said end of said shaped explosivecharge;

(h) an explosive squib seated in said bore, said squib including a casehaving anintegral sealed end, a detonating shearing charge of explosivein said case, an inert barrier plug positioned between said shearingcharge and said sealed end of said case, said barrier plug adapted todeflect the major portion of the energy resulting from detonation ofsaid shearin charge in a direction transverse to the axis of saidrestraining member; and

(i) said restraining member being adapted to shear transversely adjacentthe upper end of said squib upon detonation of said squib to permit saidshaped explosive charge to pivot from said axial disposition withoutdamage to said charge from detonation of said squib.

5. A bull nose for Well perforating assemblies having pivotable, shapedexplosive charge units axially aligned with the longitudinal axis of theassembly comprising:

(a) an open-ended main body having generally cylindrical side walls;

(b) a longitudinally extending web projecting from the interior of saidside wall;

(c) afrangible, upstanding stop post integrally formed with said web andhaving an upper portion extending thereabove;

(d) said stop post providing a downwardly opening,

7 axial bore in the lower portion thereof adapted to receive anexplosive squib; and

(e) said bore terminating a substantial distance from the upper end ofsaid stop post.

6. A bull nosev for well perforating assemblies having pivotable, shapedexplosive charge units axially aligned with the longitudinal axis of theassembly comprising:

(a) an open-ended main body having generally cylindrical side walls;

(b) a longitudinally extending web projecting from the interior of saidside wall;

(0) a frangible, upstanding'stop post integrally formed with said weband having an upper portion extending thereabove;

((1) said stop post providing an upper and a lower axial bore thereinseparated by an integral transverse wall; and

(e) the lower portion of said stop post surrounding said lower axialbore having a thin side wall immediately below said transverse walladapted to be readily sheared by the detonation of an explosive equibreceived in said lower bore.

References Cited by the Examiner UNITED STATES PATENTS 2,556,672 6/51Bergh et al. 891.5 X 2,990,774 7/61 Toelke 102-20 3,067,679 12/62Caldwell et a1. l02--20 SAMUEL FEINBERG, Primary Examiner.

1. A WELL PERFORATING ASSEMBLY COMPRISING: (A) A CARRIER; (B) A SHAPEDEXPLOSIVE CHARGE UNIT HAVING A FRANGIBLE CASE; (C) MEANS PIVOTALLYMOUNTING SAID UNIT ON SAID CARRIER IN A FIRST POSITION, SAID UNIT BEINGPIVOTABLE IN SAID MOUNTING MEANS TO A SECOND POSITION; (D) MEANS BIASINGSAID UNIT TO PIVOT FROM SAID FIRST POSITION TO SAID SECOND POSITIONS;(E) DETENT MEANS ON SAID UNIT ADJACENT TO SAID FRANGIBLE CASE; (F) AFRANGIBLE CANTILEVER STOP MEMBER HAVING ITS SUPPORTED END FIXED TO SAIDCARRIER AT A POINT REMOTE FROM SAID FRANGIBLE CASE AND ITS UNSUPPORTEDEND PROJECTING INTO ENGAGEMENT WITH SAID DETENT MEANS TO RESTRAIN SAIDUNIT FROM PIVOTING TO SAID SECOND POSITION; AND (G) AN EXPLOSIVE SQUIBLOCATED ADJACENT THE SUPPORTED END OF SAID STOP MEMBER AN ADAPTED UPONDETONATION TO SEVER THE UNSUPPORTED END OF SAID STOP MEMBER FROM THESUPPORTED END OF SAID STOP MEMBER TO PERMIT SAID UNIT TO PIVOT TO SAIDSECOND POSITION.